>> well, you know, definitive is a tough word in science because that establishes a very direct cause and effect relationship. keep in mind, when you look at these for several years now these brains have been studied of players who have died. sometimes prematurely. their brains are studied but oftentimes studied because there was a suspicion in the first place and biassed the study a little bit and what researchers are saying. be a little bit cautious interpreting the results and compelling stuff. wolf, as you mentioned, i'm researching this a long time. there's players over the years that we heard about, dave dorson, for example, he had written a letter about this. he served on some of the committees that evaluated head injuries and he himself donated the brain. he committed suicide but left a note saying to donate the brain. john mack i can, the same sort of thing. one of the most compelling things about this study is welcoming at this in stages. instead of saying someone has it or don't, they are creating stage i to stage iv for severity and based on usually how many of the blows t